AUDIO SYSTEM DESCRIPTION

Size: px

Start display at page:

Download "AUDIO SYSTEM DESCRIPTION"

Merry Porter
5 years ago
Views:

1 BE86 DESCRIPTION 1. RADIO WAVE BAND BE0AX03 The radio wave bands used in radio broadcasting are as follows: Frequency Designation 30 khz 300 khz 3 MHz 30 MHz 300 MHz LF MF HF VHF Radio wave FM Modulation method Amplitude modulation Frequency modulation LF: Low frequency MF: Medium Frequency HF: High Frequency VHF: Very High Frequency FM (Stereo) FM (Monaural) 2. SERVICE AREA There are great differences in the size of the service area for and FM monaural. Sometimes FM stereo broadcasts cannot be received even through comes in very clearly. Not only does FM stereo have the smallest service area, but it also picks up static and other types of interference ( noise ) easily. BE RECEPTION PROBLEMS Besides the problem of static, there are also the problems called fading, multipath and fade out. These problems are caused not by electrical noise but by the nature of the radio waves themselves. Fading Ionosphere Fading Besides electrical interference, broadcasts are also susceptible to other types of interference, especially at night. This is because radio waves bounce off the ionosphere at night. These radio waves then interfere with the signals from the same transmitter that reach the vehicle s antenna directly. This type of interference is called fading. BE

2 BE87 Multipath Multipath One type of interference caused by bouncing of radio waves off obstructions is called multipath. Multipath occurs when a signal from the broadcast transmitter antenna bounces off buildings and mountains and interferes with the signal that is received directly. BE2820 Fade Out Fade Out Because FM radio waves are of higher frequencies than radio waves, they bounce off buildings, mountains, and other obstructions. For this reason, FM signals often seem to gradually disappear or fade away as the vehicle goes behind a building or other obstructions. This is called fade out. BE NOISE PROBLEMS (a) Questionnaire for noise: It is very important for noise troubleshooting to have good understanding of the claims from the customers, so that make the best use of following quenstionnaire and diagnose the problem accurately. occurs at a specific place. occurs when listening to faint broadcasting. Strong possibility of foreign noise. There is a case that the same program is broadcasted from each local station and that may be the case you are listening to different station if the program is the same. FM occurs only at night. occurs while driving and at a specific place. Strong possibility of the beat from a distant broadcasting. Strong possibility of multipath noise and fading noise caused by the changes of FM waves. In the case that the noise occurrence condition does not meet any of the above quenstionnaire, check based on the Trouble Phenomenon. Refer to previous page for multipath and fading. 2307

3 BE88 (b) Matlers that require attention when checking: coming into the radio usually has no harm for practical use as the noise protection is taken and it is hardly thinkable for an extremely loud noise to come in. When extremely loud noise comes into the radio, check if the grounding is normal where the antenna is installed. Check if all the regular noise prevention parts are properly installed and if there is any installation of nonauthorized parts and nonauthorized wiring. If you leave the radio out of tune (not tuning), it is easy to diagnose the phenomenon as noise occurs frequently. Glass Printed Signal Radio N21545 (c) and noise: Electronic signal received by the antenna will reach to the radio transmitting through the core wire of the coaxial cable. Any noise wave other than radio wave is mixed into this core wire, that naturally causes noise in the radio and poor sound quality. In order to prevent these noises from mixing into the radio, the core wire inside the coaxial cable is covered with a mesh wire called shield wire. This shield wire shelters the noise and transmits it to the ground, thus preventing noise from mixing in. If this shield wire has grounding failure, that causes noise. to Radio Battery Choke Coil (d) Choke coil and noise: The choke coil is connected in the rear window defogger circuit. This is conneted so to prevent noise from mixing into the radio by making the noise current included in the power source of the rear window defogger flow to the ground. N

4 BE89 Plug (Main) (1) (3) Plug (Sub) (Main) (2) (4) (Sub) I Glass printed antenna: GROUNDING FOR THE ANTENNA CORD AND CHOKE COIL During troubleshooting, in case that the antenna code continuity check, grounding check and grounding check of the choke coil are needed, please check refering to the following illustration. connection Normal condition (1) (2) Continuity (3) (4) Continuity Ground point: Cord Choke Coil Center Brace Pillar (RH) N21548 I00403 I00402 Pillar (LH) I

5 BE90 Plug (1) (2) I Fixed mast antenna: GROUNDING FOR THE ANTENNA CORD AND CHOKE COIL During troubleshooting, in case that the antenna code continuity check, grounding check and grounding check of the choke coil are needed, please check refering to the following illustrations. connection Normal condition (1) (2) Continuity Ground point: Cord Center Brace Luggage Room (RH side) Filter I00427 I00428 I00429 Pillar (LH) I

AUDIO SYSTEM DESCRIPTION

AUDIO SYSTEM DESCRIPTION BE63 DESCRIPTION 1. RADIO WAVE BAND BE1KE01 The radio wave bands used in radio broadcasting are as follows: Frequency Designation 30 khz 300 khz 3 MHz 30 MHz 300 MHz LF MF HF VHF Radio wave AM FM Modulation